Starch comprises two polysaccharides: amylose and amylopectin. Amylose is a generally linear polymer of glucose units connected by alpha 1-4 glycosidic linkages. Amylopectin is a branched polymer in which many of the glucose units are connected by alpha 1-4 glycosidic linkages, but some are connected by alpha 1-6 glycosidic linkages.
Alpha-amylase is an enzyme that is present in the human body and which hydrolyzes alpha 1-4 linkages in starch, thus leading to digestion of the starch. In certain situations it is desirable to produce starch that resists hydrolysis by alpha-amylase, for example to decrease the caloric content of the starch, or to increase its dietary fiber content. However, attempts to produce such starch in the past have suffered from one or more problems, such as process complexity and expense, product handling difficulties, or acceptable performance in food systems. As one specific example, some alpha amylase-resistant starches have tended to comprise fine particulates which are difficult to separate from an aqueous phase.
There is a need for improved starches that are resistant to alpha-amylase and that can withstand severe food processing conditions of heating and shearing, and for improved processes for making such starches.